Nowadays, water resources are under pressure of shortage and pollution. In Korea, the average annual rainfall is higher than the amounts of world average. However, the amounts of available water resources are not enough, due to high population density and uneven seasonal distribution of rainfall. Moreover, irrigation water is one of the most important factors in agricultural activity. Many countermeasures to cope with this problem are being undertaken. One of these, the rainwater harvesting and reusing is an economical small-scale technology that is ensuring the irrigation water resource. To evaluate the possibility of reuse of drainage from plastic film house at rainy season, the change in water quality of rainwater with storage periods and yield index of Chinese cabbage with irrigation water resources were investigated. To harvest rainwater from the roof of plastic film house, simple system was established. The rainwater is collected in sedimentation tank through down-pipe and moves to rainwater reservoir by water pump. During the movement amounts of rainwater are measured by flow meter and compared with rainfall. The chemical properties of rainwater, which was collected from July to October, were analyzed. As the results, there was little loss at collecting drainage, because rainwater stored directly from the roof into the storage tank. At July, which had less amounts of rainfall, EC value showed big difference between rainwater and drainage from the roof of plastic film house. However, it didn't show any big difference of EC value and ion concentrations between rainwater and drainage after August, in which rainfall was much higher than July. There was no big change of water quality until 30 days after storage. Run-off water had high amounts of chemical components compare to rainwater and roof drainage. As flowing soil surface, it had high amounts of suspended solids. It made hard to store and reuse as irrigation water, due to clogging nozzle by soil particle and algae grown during storage. Yield index of crop showed highest value at the run-off water. Run-off water had high amounts of nitrogen and phosphorus. It acted as nutrients for growing plant. Those of roof drainage irrigation were similar with shallow groundwater, which was used as control. With these results, the rainwater, which was harvested and stored at rainy season, can be reused as irrigation water during dry season in autumn in Korea.